The steroid metabolome of adrenarche

Regulation of androgen biosynthesis - A short review and preliminary results from the hyperandrogenic starvation NCI-H295R cell model

Regulation of androgen production is poorly understood. Adrenarche is the physiologic event in mid-childhood when the adrenal zona reticularis starts to produce androgens through specific expression of genes for enzymes and cofactors necessary for androgen synthesis. Similarly, expression and activities of same genes and products are deregulated in hyperandrogenic disorders such as the polycystic ovary syndrome (PCOS). Numerous studies revealed involvement of several signaling pathways stimulated through G-protein coupled receptors or growth factors transmitting their effects through cAMP- or non-cAMP-dependent signaling. Overall a complex network regulates androgen synthesis targeting involved genes and proteins at the transcriptional and post-translational levels. Newest players in the field are the DENND1A gene identified in PCOS patients and the MAPK14 which is the kinase phosphorylating CYP17 for enhanced lyase activity. Next generation sequencing studies of PCOS patients and transcriptome analysis of androgen producing tissues or cell models provide newer tools to identify modulators of androgen synthesis.

CYB5A polymorphism increases androgens and reduces risk of rheumatoid arthritis in women

Introduction

Rheumatoid arthritis (RA) is characterized by decreased androgen levels, which was the first hormonal abnormality described. Several studies indicated that steroidogenesis is directed towards endogenous glucocorticoids at the expense of androgens. The decisive step governing androgen synthesis is the 17,20-lyase activity of the CYP17A1 gene-encoded enzyme cytochrome P450 17A1. Here, we focused on the role in RA of the critical cofactor for 17,20-lyase activity, cytochrome b5, encoded by the CYB5A gene.

Methods

Data sets of two genome wide RA association studies (GWAS) were screened for single nucleotide polymorphisms (SNP) in the CYB5A gene. Candidate SNPs in CYB5A were studied in a case–control study population of Slovakia. Expression analyses were done in synovial fibroblasts from RA patients by quantitative real-time polymerase chain reaction, and cytochrome b5–expression was detected by immunohistochemistry. Real-life androgen production after steroid conversion was measured using radiolabeled substrates.

Results

The study identified the RA-associated intronic SNP rs1790834 in the CYB5A gene in one GWAS and confirmed the same SNP in our study. The minor allele reduced RA risk selectively in women (P = 4.1*10⁻³; OR = 0.63, 95% CI [0.46-0.86]). The protective effect was confined to rheumatoid factor-positive (OR = 0.53, [0.37-0.75]) and anti-cyclic citrullinated peptide-positive (OR = 0.58, [0.41-0.83]) cases, respectively. The protective allele doubles CYB5A mRNA-expression resulting in 2-3fold activation of steroid 17,20-lyase activity, and protective allele was accompanied by a higher density of cytochrome b5-positive cells in synovial tissue.

Conclusions

CYB5A is the first RA susceptibility gene involved in androgen synthesis. Our functional analysis of SNP rs1790834 indicates that it contributes to the sex bias observed in RA.

Dual-axis hormonal covariation in adolescence and the moderating influence of prior trauma and aversive maternal parenting

Adversity early in life can disrupt the functioning of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes and increase risk for negative health outcomes. The interplay between these axes and the environment is complex, and understanding needs to be advanced by the investigation of the multiple hormonal relationships underlying these processes. The current study examined basal hormonal associations between morning levels of cortisol, testosterone, and dehydroepiandrosterone in a cohort of adolescents (mean age 15.56 years). The moderating influence of childhood adversity was also examined, as indexed by self-reported trauma (at mean age 14.91), and observed maternal aggressive parenting (at mean age 12.41). Between-person regressions revealed significant associations between hormones that were moderated by both measures of adversity. In females, all hormones positively covaried, but also interacted with adversity, such that positive covariation was typically only present when levels of trauma and/or aggressive parenting were low. In males, hormonal associations and interactions were less evident; however, interactions were detected for cortisol-testosterone - positively covarying at high levels of aggressive parenting but negatively covarying at low levels - and DHEA-cortisol - similarly positively covarying at high levels of parental aggression. These results demonstrate associations between adrenal and gonadal hormones and the moderating role of adversity, which is likely driven by feedback mechanisms, or cross-talk, between the axes. These findings suggest that hormonal changes may be the pathway through which early life adversity alters physiology and increases health risks, but does so differentially in the sexes; however further study is necessary to establish causation.

Premature adrenarche: etiology, clinical findings, and consequences

Adrenarche means the morphological and functional change of the adrenal cortex leading to increasing production of adrenal androgen precursors (AAPs) in mid childhood, typically at around 5-8 years of age in humans. The AAPs dehydroepiandrosterone (DHEA) and its sulfate conjugate (DHEAS) are the best serum markers of adrenal androgen (AA) secretion and adrenarche. Normal ACTH secretion and action are needed for adrenarche, but additional inherent and exogenous factors regulate AA secretion. Inter-individual variation in the timing of adrenarche and serum concentrations of DHEA(S) in adolescence and adulthood are remarkable. Premature adrenarche (PA) is defined as the appearance of clinical signs of androgen action (pubic/axillary hair, adult type body odor, oily skin or hair, comedones, acne, accelerated statural growth) before the age of 8 years in girls or 9 years in boys associated with AAP concentrations high for the prepubertal chronological age. To accept the diagnosis of PA, central puberty, adrenocortical and gonadal sex hormone secreting tumors, congenital adrenal hyperplasia, and exogenous source of androgens need to be excluded. The individually variable peripheral conversion of circulating AAPs to biologically more active androgens (testosterone, dihydrotestosterone) and the androgen receptor activity in the target tissues are as important as the circulating AAP concentrations as determinants of androgen action. PA has gained much attention during the last decades, as it has been associated with small birth size, the metabolic and polycystic ovarian syndrome (PCOS), and thus with an increased risk for type 2 diabetes and cardiovascular diseases in later life. The aim of this review is to describe the known hormonal changes and their possible regulators in on-time and premature adrenarche, and the clinical features and possible later health problems associating with PA.

Regulation of human 3β-hydroxysteroid dehydrogenase type 2 by adrenal corticosteroids and product-feedback by androstenedione in human adrenarche

In human adrenarche during childhood, the secretion of dehydroepiandrosterone (DHEA) from the adrenal gland increases due to its increased synthesis and/or decreased metabolism. DHEA is synthesized by 17α-hydroxylase/17,20-lyase, and is metabolized by 3β-hydroxysteroid dehydrogenase type 2 (3βHSD2). In this study, the inhibition of purified human 3βHSD2 by the adrenal steroids, androstenedione, cortisone, and cortisol, was investigated and related to changes in secondary enzyme structure. Solubilized, purified 3βHSD2 was inhibited competitively by androstenedione with high affinity, by cortisone at lower affinity, and by cortisol only at very high, nonphysiologic levels. When purified 3βHSD2 was bound to lipid vesicles, the competitive Ki values for androstenedione and cortisone were slightly decreased, and the Ki value of cortisol was decreased 2.5-fold, although still at a nonphysiologic level. The circular dichroism spectrum that measured 3βHSD2 secondary structure was significantly altered by the binding of cortisol, but not by androstenedione and cortisone. Our import studies show that 3βHSD2 binds in the intermitochondrial space as a membrane-associated protein. Androstenedione inhibits purified 3βHSD2 at physiologic levels, but similar actions for cortisol and cortisone are not supported. In summary, our results have clarified the mechanisms for limiting the metabolism of DHEA during human adrenarche.

Dehydroepiandrosterone-induces miR-21 transcription in HepG2 cells through estrogen receptor β and androgen receptor

Although oncomiR miR-21 is highly expressed in liver and overexpressed in hepatocellular carcinoma (HCC), its regulation is uncharacterized. We examined the effect of physiologically relevant nanomolar concentrations of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S) on miR-21 expression in HepG2 human hepatoma cells. 10nM DHEA and DHEA-S increase pri-miR-21 transcription in HepG2 cells. Dietary DHEA increased miR-21 in vivo in mouse liver. siRNA and inhibitor studies suggest that DHEA-S requires desulfation for activity and that DHEA-induced pri-miR-21 transcription involves metabolism to androgen and estrogen receptor (AR and ER) ligands. Activation of ERβ and AR by DHEA metabolites androst-5-ene-3,17-dione (ADIONE), androst-5-ene-3β,17β-diol (ADIOL), dihydrotestosterone (DHT), and 5α-androstane-3β,17β-diol (3β-Adiol) increased miR-21 transcription. DHEA-induced miR-21 increased cell proliferation and decreased Pdcd4 protein, a bona fide miR-21. Estradiol (E2) inhibited miR-21 expression via ERα. DHEA increased ERβ and AR recruitment to the miR-21 promoter within the VMP1/TMEM49 gene, with possible significance in hepatocellular carcinoma.

Serum androgen bioactivity is low in children with premature adrenarche

BACKGROUND

Clinical findings in children with premature adrenarche (PA) correlate only partly with circulating levels of adrenal androgens. It is not known whether the prepubertal low circulating concentrations of testosterone (T) and dihydrotestosterone, together with those of adrenal androgens, are capable of activating the androgen receptor.

METHODS

This cross-sectional study was performed at a university hospital. Circulating androgen bioactivity was measured in 67 prepubertal children with clinical signs of PA and 94 control children using a novel androgen bioassay.

RESULTS

Circulating androgen bioactivity was low in the PA and control children. In the subgroup of children (n = 28) with serum T concentration over the assay sensitivity (0.35 nmol/l) and a signal in the androgen bioassay, we found a positive correlation between androgen bioactivity and serum T (r = 0.50; P < 0.01) and the free androgen index (r = 0.61; P < 0.01) and a negative correlation with serum sex hormone-binding globulin concentration (r = -0.41; P < 0.05).

CONCLUSION

Peripheral metabolism of adrenal androgen precursors may be required for any androgenic effects in PA. However, the limitations in the sensitivity of the bioassay developed herein may hide some differences between the PA and control children.

Study protocol: imaging brain development in the Childhood to Adolescence Transition Study (iCATS)

Background

Puberty is a critical developmental phase in physical, reproductive and socio-emotional maturation that is associated with the period of peak onset for psychopathology. Puberty also drives significant changes in brain development and function. Research to date has focused on gonadarche, driven by the hypothalamic-pituitary-gonadal axis, and yet increasing evidence suggests that the earlier pubertal stage of adrenarche, driven by the hypothalamic-pituitary-adrenal axis, may play a critical role in both brain development and increased risk for disorder. We have established a unique cohort of children who differ in their exposure to adrenarcheal hormones. This presents a unique opportunity to examine the influence of adrenarcheal timing on brain structural and functional development, and subsequent health outcomes. The primary objective of the study is to explore the hypothesis that patterns of structural and functional brain development will mediate the relationship between adrenarcheal timing and indices of affect, self-regulation, and mental health symptoms collected across time (and therefore years of development).

Methods/Design

Children were recruited based upon earlier or later timing of adrenarche, from a larger cohort, with 128 children (68 female; M age 9.51 years) and one of their parents taking part. Children completed brain MRI structural and functional sequences, provided saliva samples for adrenarcheal hormones and immune biomarkers, hair for long-term cortisol levels, and completed questionnaires, anthropometric measures and an IQ test. Parents completed questionnaires reporting on child behaviour, development, health, traumatic events, and parental report of family environment and parenting style.

Discussion

This study, by examining the neurobiological and behavioural consequences of relatively early and late exposure to adrenarche, has the potential to significantly impact our understanding of pubertal risk processes.

Marked elevation of adrenal steroids, especially androgens, in saliva of prepubertal autistic children

Autism is diagnosed on the basis of behavioral manifestations, but its biomarkers are not well defined. A strong gender bias typifying autism (it is 4-5 times more prevalent in males) suggests involvement of steroid hormones in autism pathobiology. In order to evaluate the potential roles of such hormones in autism, we compared the salivary levels of 22 steroids in prepubertal autistic male and female children from two age groups (3-4 and 7-9 years old) with those in healthy controls. The steroids were analyzed using gas chromatography-mass spectrometry and radioimmunoassay. Statistical analysis (ANOVA) revealed that autistic children had significantly higher salivary concentrations of many steroid hormones (both C21 and C19) than control children. These anomalies were more prominent in older autistic children and in boys. The levels of androgens (androstenediol, dehydroepiandrosterone, androsterone and their polar conjugates) were especially increased, indicative of precocious adrenarche and predictive of early puberty. The concentrations of the steroid precursor, pregnenolone, and of several pregnanolones were also higher in autistic than in healthy children, but cortisol levels were not different. Some steroids, whose levels are raised in autism (allopregnanolone, androsterone, pregnenolone, dehydroepiandrosterone and their sulfate conjugates) are neuroactive and modulate GABA, glutamate, and opioid neurotransmission, affecting brain development and functioning. These steroids may contribute to autism pathobiology and symptoms such as elevated anxiety, sleep disturbances, sensory deficits, and stereotypies among others. We suggest that salivary levels of selected steroids may serve as biomarkers of autism pathology useful for monitoring the progress of therapy.

11β-hydroxyandrostenedione, the product of androstenedione metabolism in the adrenal, is metabolized in LNCaP cells by 5α-reductase yielding 11β-hydroxy-5α-androstanedione

11β-Hydroxyandrostenedione (11OHA4), which is unique to the adrenal, was first isolated from human adrenal tissue in the fifties. It was later shown in the sixties that 11β-hydroxytestosterone (11OHT) was also produced by the human adrenal. Attention has shifted back to these adrenal androgens once more, as improved analytical techniques have enabled more accurate detection of steroid hormones. In this paper, we investigated the origin of these metabolites as well as their subsequent metabolism and examined a possible physiological role for 11OHA4 in prostate cancer cells. In H295R cells treated with forskolin and trilostane, etomidate, a reported cytochrome P450 11β-hydroxylase (CYP11B1) inhibitor, blocked the production of corticosterone, cortisol, 11OHA4 and 11OHT. The metabolism of androstenedione and testosterone by CYP11B1 and aldosterone synthase (CYP11B2) was assayed. Androstenedione was converted by CYP11B1, while the conversion by CYP11B2 was negligible. Both enzymes readily converted testosterone. The metabolism of these 11β-hydroxylated metabolites by 11β-hydroxysteroid dehydrogenase (11βHSD) types 1 and 2 was subsequently investigated. 11βHSD2 catalyzed the conversion of both 11OHA4 and 11OHT to their respective keto-steroids, while 11βHSD1 catalyzed the conversion of 11-ketoandrostenedione and 11-ketotestosterone to their respective hydroxy-steroids in Chinese hamster ovary cells. Investigating a functional role, steroid 5α-reductase types 1 and 2 converted 11OHA4 to 11β-hydroxy-5α-androstanedione (11OH-5α-dione), identified by accurate mass detection. UPLC-MS/MS analyses of 11OHA4 metabolism in LNCaP androgen-dependent prostate cancer cells, identified the 5α-reduced metabolite as well as 11-ketoandrostenedione and 11-ketotestosterone, with the latter indicating conversion by 17β-hydroxysteroid dehydrogenase. Downstream metabolism by 11βHSD2 and by 5α-reductase may therefore indicate a physiological role for 11OHA4 and/or 11OH-5α-dione in normal and prostate cancer cells.

Methodological considerations in use of the cortisol/DHEA(S) ratio in adolescent populations

OBJECTIVE

The cortisol/DHEA(S) ratio has demonstrated utility in studies of HPA activity and psychopathology. However, use of the cortisol/DHEA(S) ratio in adolescent populations requires additional consideration of differential changes in DHEA(S) and cortisol during the course of puberty. This study examines the relationship between pubertal status and individual cortisol and DHEAS levels as well as with the cortisol/DHEAS ratio.

METHOD

Morning salivary cortisol and urinary DHEAS levels were obtained for 267 young adolescents at three time points, each approximately one year apart. Growth curve modeling and repeated measures ANOVA were used to assess the effect of adrenal development on individual hormone levels and on the total ratio.

RESULTS

Pubic hair development was a significant predictor of change over time in DHEAS but not cortisol. Development was also a significant predictor of the cortisol/DHEAS ratio when raw cortisol and DHEAS values were used.

CONCLUSIONS

Our findings indicate that, when DHEAS levels were adjusted to control for pubertal status, the ratio demonstrated stability over time. This finding is in line with the hypothesis that the ratio may tap stable individual differences in HPA functioning.

Interactive effects of dehydroepiandrosterone and testosterone on cortical thickness during early brain development

Humans and the great apes are the only species demonstrated to exhibit adrenarche, a key endocrine event associated with prepubertal increases in the adrenal production of androgens, most significantly dehydroepiandrosterone (DHEA) and to a certain degree testosterone. Adrenarche also coincides with the emergence of the prosocial and neurobehavioral skills of middle childhood and may therefore represent a human-specific stage of development. Both DHEA and testosterone have been reported in animal and in vitro studies to enhance neuronal survival and programmed cell death depending on the timing, dose, and hormonal context involved, and to potentially compete for the same signaling pathways. Yet no extant brain-hormone studies have examined the interaction between DHEA- and testosterone-related cortical maturation in humans. Here, we used linear mixed models to examine changes in cortical thickness associated with salivary DHEA and testosterone levels in a longitudinal sample of developmentally healthy children and adolescents 4-22 years old. DHEA levels were associated with increases in cortical thickness of the left dorsolateral prefrontal cortex, right temporoparietal junction, right premotor and right entorhinal cortex between the ages of 4-13 years, a period marked by the androgenic changes of adrenarche. There was also an interaction between DHEA and testosterone on cortical thickness of the right cingulate cortex and occipital pole that was most significant in prepubertal subjects. DHEA and testosterone appear to interact and modulate the complex process of cortical maturation during middle childhood, consistent with evidence at the molecular level of fast/nongenomic and slow/genomic or conversion-based mechanisms underlying androgen-related brain development.

Effect of dehydroepiandrosterone on atopic dermatitis-like skin lesions induced by 1-chloro-2,4-dinitrobenzene in mouse

BACKGROUND

Th2 cells are overexpressed in the skin and serum of atopic dermatitis (AD) patients. Previously, we found that dehydroepiandrosterone (DHEA) decreased eosinophil infiltration in asthmatic mice through the suppression of Th2-associated cytokines. Therefore, we hypothesized that DHEA might improve the symptoms of AD syndrome.

OBJECTIVE

In this study, we evaluated the symptom improvement and anti-inflammatory response that result from the modulation of immunity by DHEA modulated in AD-like mice.

METHODS

Female BALB/c mice were sensitized and challenged with 1-chloro-2,4-dinitrobenzene. On days 14-29 after sensitization, mice were treated with cutaneous (skin smear) or oral administration of DHEA. In addition, human keratinocyte (HaCat) cells were used to evaluate the effect of DHEA on the in vitro production of proinflammatory cytokines and chemokines.

RESULTS

Both cutaneous and oral DHEA were able to decrease ear swelling and skin inflammation in AD-like mice. DHEA also attenuated eosinophil and mast cell infiltration into ear and skin tissue. Additionally, Th2-associated cytokines were inhibited in splenocyte culture, and suppressed the levels of IgE and interleukin 4 in serum. Oral and cutaneous administration of DHEA reduced the inflammatory response, as evidenced by AD-like skin lesions, in a similar manner. DHEA significantly reduced inflammatory cytokines and chemokines through the nuclear factor-κB and mitogen-activated protein kinases pathways in tumor necrosis factor-α activated HaCat cells.

CONCLUSION

DHEA ameliorates AD-like mouse skin inflammation and reduces eosinophil and mast cell infiltration by reducing the production of Th2-associated cytokines and chemokines.

Cytochrome b5: novel roles in steroidogenesis

Cytochrome b(5) (cyt-b(5)) is essential for the regulation of steroidogenesis and as such has been implicated in a number of clinical conditions. It is well documented that this small hemoprotein augments the 17,20-lyase activity of cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17A1). Studies have revealed that this augmentation is accomplished by cyt-b(5) enhancing the interaction between cytochrome P450 reductase (POR) and CYP17A1. In this paper we present evidence that cyt-b(5) induces a conformational change in CYP17A1, in addition to facilitating the interaction between CYP17A1 and POR. We also review the recently published finding that cyt-b(5) allosterically augments the activity of 3β-hydroxysteroid dehydrogenase/Δ(5)-Δ(4) isomerase (3βHSD), a non cytochrome P450 enzyme, by increasing the enzymes affinity for its cofactor, NAD(+). The physiological importance of this finding, in terms of understanding adrenal androstenedione production, is examined. Finally, evidence that cyt-b(5) is able to form homomeric complexes in living cells is presented and discussed.